Chitosan is excellent in physicochemical adsorptivity, biocompatibility and biodegradability and accordingly, the chitosan is a biopolymer which has been able to widely be used in various industrial fields as, for instance, a material for medicine/medical treatment, perfumes, cosmetics, adhesive/paints and varnishes, and duplication/recording-display. On the other hand, porous beads whose particle size does not widely vary have been used, as carriers for immobilization of, for instance, enzymes, in a wide variety of industrial fields such as chemical industries, medical treatments, food industries and industrial processes. For this reason, if porous beads of chitosan having a uniform particle size can be provided, they may be used and utilized in a variety of fields.
Chitosan beads have conventionally been produced by, for instance, the following complicated method. First of all, inorganic substances are removed from components which constitute the exoskeleton of crustaceans to give chitosan and then the resulting chitosan is sufficiently dissolved in an organic acid to form a uniform dope. This dope is dropwise added to or discharged into a basic coagulating liquid to thus give chitosan beads (see Knorr, D., M. Daly: Mechanics and diffusional changes observed in multi-layer chitosan/alginate coacervate capsules, Process Biochemistry, 1988, 4, pp. 48-50).